I know the feeling. Just a few years ago, I lost my kitty Tiffany, to the neighbor's dog. She was all white with a red nose. Her lifelong friend Timmy (my other cat, also all white) would search all over the house for her, crying out for Tiffany. He never understood what happened to his little friend. The thing with pets is that they cannot grasp the concept of death, or birth for that matter, so they do not understand when one of their pack suddenly goes missing. I know it is very hard to lose such a good friend like that, but I am thankful that your cat had a great home while she was alive, I bet she was very happy. I'll be praying for you!!!
Oh her brother is looking for her all the time. My daughter asked me this morning if I'll get her a new kitty.